Double tracking is a recording technique where you record the initial guitar track, then record a second guitar track that mirrors the performance of the first track. When you play back the tracks, you can pan one of the tracks in the mix to the left and pan the other track to the right. You can also pan the tracks the same and do a 60-40 volume mix (one track 20% lower than the other track) or experiment with different volume levels between the two recorded tracks.

If you want a really wide sound, you can layer multiple tracks. Try recording four takes of the same track. The main thing is to enhance the first take and create a wider or bigger sound. Many artists, producers and engineers have used this technique in the studios for years such as The Beatles, Pink Floyd and Steely Dan.

Tech info: PAN is short for Panoramic Potentiometer (pan pot). On most mixing consoles, the pan knob is located in each input module and is the control that distributes a signal to two channels or speakers in an adjustable ratio. The pan pot dictates the location of the recorded signal, sonically imaged between stereo speakers.
–Mike Harrison